No it wasn't revealed how large a Federation fleet was. The Seventh Fleet is the only time we get a solid number. However, "Favors the Bold" suggests that a Fleet can be much larger. The fleet that heads for DS9 was around 600 strong and were made up of two fleets, the 2nd and 5th, so if it was an even split and no other smaller units joined the size of a fleet can be 300+. Sisko's plan was for "elements" of these fleets to take part so this figure could keep going upwards.

As for Klingon ships in the Seventh Fleet there could have been. Memory Alpha identifies the fleet shoots we see at the end of "Call to Arms" and the 1st episode of season 6 as the Second Fleet and we see both Klingon and Starfleet vessels in the group. However, I don't remember it been identified on screen as the 2nd fleet so I'm not sure where MA came up with that idea. Regardless of that we do see that Klingon and Starfleet operated together, so if you want there to be Klingon ships there I don't think there is anything that would argue that they weren't here.